Relays are electromechanical switches operated by a flow of electricity in one circuit and controlling the flow of electricity in another circuit. A typical relay includes an electromagnet with a soft iron bar, called an armature, held close to it. A movable contact is connected to the armature in such a way that the contact is held in its normal position by a spring. When the electromagnet is energized, it exerts a force on the armature that overcomes the pull of the spring and moves the contact so as to either complete or break a circuit. When the electromagnet is de-energized, the contact returns to its original position.
Latching relays are the types of relays which can maintain closed and open contact positions without energizing an electromagnet. Short current pulses are used to temporally energize the electromagnet and switch the relay from one contact position to the other. An important advantage of latching relays is that they do not consume power (actually they do not need a power supply) in the quiescent state.
Conventional electromechanical relays have traditionally been fabricated one at a time, by either manual or automated processes. The individual relays produced by such an “assembly-line” type process generally have relatively complicated structures and exhibit high unit-to-unit variability and high unit cost. Conventional electromechanical relays are also relatively large when compared to other electronic components. Size becomes an increasing concern as the packaging density of electronic devices continues to increase.
Two forms of conventional latching relays are described in the Engineers' Relay Handbook (Page 3-24, Ref. [1]). A permanent magnet supplies flux to either of two permeable paths that can be completed by an armature. To transfer the armature and its associated contacts from one position to the other requires energizing current through the electromagnetic coil using the correct polarity. One drawback of these traditional latching relay designs is that they require the coil to generate a relatively large reversing magnetic field in order to transfer the armature from one position to the other. This requirement mandates a large number of wire windings for the coil, making the coil size large and impossible or very difficult to fabricate other than using conventional winding methods.
U.S. Pat. No. 5,818,316 issued to Shen et al. described a switch having two magnetizable conductors in which the first conductor is permanently magnetized and the second conductor is switchable in response to a magnetic field applied thereto.
U.S. Pat. No. 6,469,602 B2 issued to Ruan et al. described a relay operated by providing a cantilever sensitive to magnetic fields such that the cantilever exhibits a first state corresponding to the open state of the relay and a second state corresponding to the closed state of the relay.
U.S. Pat. No. 6,124,650 issued to Bishop et al. disclosed a relay employing square-loop latchable magnetic material having a magnetization direction capable of being changed in response to exposure to an external magnetic field. The magnetic field is created by a conductor assembly. The attractive or repulsive force between the magnetic poles keeps the switch in the closed or open state.
Each of the aforementioned relays, though providing a unique approach to make latching electromechanical relays, has drawbacks and limitations. Some of them may require large current for switching, and some may require precise relative placement of individual components. These drawbacks and limitations can make manufacturing difficult and costly, and hinder their value in practical applications.
Accordingly, it would be highly desirable to provide an easily switchable electromechanical relay which is also simple and easy to manufacture and use.
It is a purpose of the present invention to provide a new and improved electromechanical relay which can be easily configured as latching or non-latching types.
It is another purpose of the present invention to provide a new and improved multi-pole multi-throw electromechanical relay.